Hydrogenation of naphthalene



Patented Apr. 27, 1926. 7

GEORG SCHROETER, F BERLIN, GERMANY.

HYDROGENA'IION OF NAPHTHALENE.

No Drawing.

Application filed August 29, 1921. Serial No. 496,639.

(GRANTED UNDER ,THE PROVISIONS OF THE AC1 OF MARCH 3, 1921, 41 STAT. In, 1313.)

To all whom it may concern:

Be it known that I, Gnone Sonnonrnn, a citizen of the German Republic, residing at Berlin, Germany, have invented certain new If and useful Improvements in Hydrogenation of Naphthalene (for 'which I have filed ap )lications in Germany February 21, 1915, atent No. 324,861, issued to assignec, Tetralin G. m. b. H.; in Germany December 7,

1915, Patent No. 324,862, issued to assignee, Tetralin G. in. b. H.; in Germany May 13, 1916, Patent No. 324,863, issued to assignee, 'letralin G. in. b. 11.; and in Belgium filed May 31, 1920: in France filed May 21, 1920;

in England filed July 8, 1920; in Italy filed June 30, 1920; in Austria filed April 15, 1920; in Hungary filed July 31, 1917; in Netherlands filed April 21, 1920; in Switzerland" filed June 30, 1920, and in Czechoslo- 2 .vakia. filed July 10, 1920), of which the fol lowing is a specification.

The present invention relates to the hydrogenation of commercial naphthalene in a technical manner, whereby products can be produced on a technical scale which are suitable for various purposes, such as substitutes for mineral oil distillates, including gasoline, burning oils and lubricating oils.

The process involves, first, the removal from commercial naphthalene of substances which, in accordance with the present invention, have been found to exert a poisoning action on hydrogenation catalyzers, and the subsequent hydrogenation of the naph- 3 izhalene while in the presence of a metal catayzer.

The hydrogenation of naphthalene, broadly stated, has heretofore been proposed, but seems not to have come into commercial use prior to the present invention.

Among the methods heretofore proposed may be mentioned the treatment of naphthalene at a high temperature with hydriodic acid (Berichte, vol. 16, page 3028), or by heating with sodium and amyl alcohol (Berichte, vol. 23, page 1561). These processes were so expensive that they could not be commercially employed.

Processes have also been proposed for the hydrogenation of naphthalene by treating.

the napththalene with hydrogen gas in the presence of a catalyst such as nickel. These processes, to the best of my knowledge, have amounts of impurities, especially methylated coumarone and corresponding sulfur compounds, which substances cause a red coloration when commercial naphthalene is subjected to treatment with hot concentrated sulfuric acid. It was also known that by boiling commercial naphthalene with acetate of mercury in alcoholic solution, certain mercury compounds were produced which were not mercury'compounds of thionaphthones. It has also previously been known that ordinary purified naphthalene contains sulfur compounds and it has been proposed to purify naphthalene from these sulfur compounds by repeated crystallization from various organic solvents. .Such processes would, however, not be commercially feasible in connection with the commercial hydrogenation of naphthalene.

In accordance with the present invention, the naphthalene treated, namely, commercial or technical naphthalene, can be purified b treating it. in a molten state with fullers earth, infusorialearth, animal charcoal or the like, that is, any porous and finelydivided material, which naturally contains small quantities of metal oxides, such as lime, and which material is also capable of absorbing or adsorbing coloring matters, resinous substances or other materials of high molecular weight. The naphathalene can then be removed by filtering or by dis- .tillation at a temperature which is not sufiiciently high to cause undesired side reactions, for example in vacuo. This purification may sometimes not be sufiiciently complete and a more complete purification can be effected by the use, instead of the above mentioned porous materials alone, of fullers earth upon which is precipitated at small amount say, 1 or 2% or so, of reduced nickel, reduced iron or other like metal. During this purification step, it is advisable to agi tate by stirring, pumping etc., in the presence of hydrogen. The temperature in this operation should be kept above 100 C. These metals also can be used alone ln/a finely-divided state for the purificationof naphthalene. Another method of purifying the naphthalene, which reduces the impurities to a very small quantity, involves the treatment of the molten naphthalene with small percentages of metallic sodium or potassium or other easily melted metals of like properties. In this operation it is advisable to treat the molten naphthalene with, say, from one-half to one and one-half per cent of metallic sodium or potassium at a temperature above 100 0., for several hours.

Another useful method of purifying the naphthalene is by treating the same n a molten state (after a preliminary distillation if desired) with small amounts of metal compounds which contain a metal loosely combined with a non-acid radical or element. Examples of such compounds are the metalammonia compounds, metal amids (such as sodium or potassium amid), metal carbides (such as aluminum or calcium carbides), or other metal compounds of acetylene.

It is, of course, to be understood that these various methods of purification above given can be used each by itself, or two or more of these methods can be used in conjunction with each other.

Naphthalene purified according to the above rocesses does not produce any red coloration when treating with concentrated sulfuric acid and the purification should be so complete that even when the naphthalene so purified is ground up'with hot concentrated sulfuric acid and allowed to stand hot for several hours, no substantial amount of red coloration is produced. If it is found that the purification of a particular batch has not been sufficiently completed, it is advisable to again subject this material to a retreatment according to one or the other of the above mentioned processes.

The naphthalene, after its purification, can be separated from the residue of the pnrifying agents, or from the compounds produced by the union of the impurities with the purifying agents, by hot pressure filtratron 1n hydrogen, or by distillation at a relatlvely low temperature, distillation in vacuo being a preferred mode of operation. The purified naphthalene can then be subected to hydrogenation, for example by addrug a catalyzer such as finely-divided nickel or nickel deposited upon fullers earth or like carrier in an autoclave under a pressure of, say, 10 atmospheres at a temperature of over C., and preferably between 150 and 200 0., while agitating.

The following examples of procedure falling within the scope of the present invention are given for the purpose of more fully explaining the matter of the invention, but the scope of the invention is not limited to these specific examples.

Ema/mole 1.-100 kilos of commercial naphthalene in a kettle at a temperature above 100 C., are stirred with 5 to 10% or more of finely divided absorbent earth, until a sample of the material, after being substantially separated, shows no red coloration when treated wit-h concentrated sulfuric acid, after standing for some time. The purified naphthalene in molten state is then mixed with 5 to 10% of a catalyzer such as fullers earth carrying 5% or so of reduced nickel placed in an autoclave and subjected to hydrogen under a pressure of, say, 10 atmospheres. The reaction mass is agitated in order to facilitate mixing withhydrogen. The temperature should be kept continuously above 100 0,, preferably between 150 and 200 C. After 3 kilos of hydrogen have been absorbed (which should require about an hours time) the liquid material is drawn elf, leaving the catalyzer in the autoclave and a new batch of 100 kilos of naphthalene is introduced and the operation repeated. This produces substantially pure tetrahydronaphthalene. The product is a colorless liquid which boils at 206 to 207 0., at atmospheric pressure or at about 88 under a pressure of 13 m. m., of mercury, it solidifies at about minus 30 C. Its flash point is 75.80? C.

In this example it is not necessary to stop the hydrogenation at the time when the naphthalene has been converted into tetraliydronaphthalene, but the operation can be continued further, in which case thehydrogenation proceeds somewhat more slowly, until after an absorption of 7.5 kgs., of hydrogen (which may require about three hours) the end product will be decahydronaphthalene, C H having a boiling point at ordinary atmospheric pressure of 188 (1., a boiling point under a pressure of 13 m. m., of mereury of 73 to- 74 C., and a flash point of 585 C.

In this example, if the amount of catalyzer is increased, the speed of hydrogenation is accelerated. One may measure the hydrogen consumption or absorption by means of the pressure gauge on the autoclave.

In the production of the tetrahydronaphthalene it has been found in operation of the present process that substantially the entire amount of naphthalene was converted into tetrahydronaphthalene before any material amount of the naphthalene will be converted into more highly hydrogenated products. This fact is somewhat surprising in V ew of the contrarystatements of Willstatter et a1. (Berichtevol; 45 page 1474 and Example 25400 kilos of commercial naphthalene, e. that obtained byv hot pressing naphthalene press cake, are stirred du'ced pressure fi'onrthe' purifying agents,

6 "from ,catalyzer poisons.

t with 200 parts of a catalytic' mixture1con-- taining about 25% of finely-divided nickel .y ide'd porous materials if desired. The testm after it has been fshown by asulfuric acid 'tcst(see aboveythat the purification is complete. "The 'hydrogenation' maybe carried out in accordance with that given in exai'nple 1. 20

naphthalene are placed in a kettle or=boiler "Ema/mph; 3. 100kilos of commercial with a} distilling tube and receiver tolbe connected therewith and mixed with-750 grams (three quarters of one percent) a of sodium and stirred :for 2 01 3- -hours at 180 to, 200 (1, whereupon the naphthalene ,isfdistilled off in vacuo. This givesa very complete '1 purification of the naphthalene '1 In this 'example,; the;' sodium can be used with the finelydiav a p and hydrogenation maybe carried out- 1 as above describedi Ea'mnple 4. 500 parts of commercial naphthalen after purification by melting with fullers earth'or'other porous materials -.coal tar still residues (after oddim;

fi ng froin'the precipitate, "are mix d precipitated on a porouscarrien'and heated inn pi'essure-receptacle with hydrogen to 1Q'O to 150 (3., and thereafter hydrogen is pumped in in such quantity that under the temperature and pressure conditions stated sufficient hydrogenis present for the complete hydrogenation of the naphthalene (that tosay to each molecule of naphthalene there are present five molecules of hydrogen). The higher pressures (that is to say pressures substantially above 10 atmospheres) are of little importance, although at pressures between 50 and 100 atmospheres the hydrogenation proceeds a little faster than at pressures of from 3 to 10 atmospheres. Stirring or shaking of the apparatus is not necessary since the catalytic material of the mass retains its spongy structure, nevertheless a very large surface is essential. The course of the reaction can be observed on the manometer provided on the apparatus, which shows a rapid fall,.and the operation should be completed in about one and one-half to three hours, at which timethe manometer will remain stationary.

The damp mass is taken from the apparaand as a startin chemical "processes.

Si ight' but not. disagreeable odor, is indifferent to permanganate a'ndbromin and seems totbe identical. with the known dccahydrouaphthalene G H It can be used as a substitute for kerosene for lamps, as

a motor fuel, as a fine lubricating oi1, as

amaterial for the production ofyexplosives g, material for various lfthe hydrogenation. is not carriedout o i a I with varying q mntltles of products less highly hydrogenated, whose presence is, observed by higherboilingpoint and higher density. of

-=the' fr 'action"1iroducecl near the end of the coinpletelythe product may consist of dec-" ahydronaphthalenc mixed distillation:operation. One can, therefore,

obtain lower hydrogenated products by this process. .The catalyzer, may be reusedfor :the hydrogenation of further quantities of inapht l alene, but. after many operations the c'atalyzrybecomes inefficient and should be regeneratediiranv suitable manner.

. i Ewample 5. Ih0,; ki 10S- of crude naphthalene in the shape 0 press cake"ob-. tained by thewarnrpressingp rocess from 1 distillation iffthe mechanical impuriti eg nd higher boiling point tarry components 9 present in relatively large amount)- are treated in a molten state with one 'kilo of sodium amid stirring activelyin' a kettle for three hours, while the naphthalene is inj'a molten condition. Theso treated naphthalene is separated from the other reaction products, preferably by distillation in vacuo. This vnaphthaleneis found to give no red color, even after standing for several hours with concentrated sulfuric acid, and can then be hydrogenated according to the process mentioned under example 1, or' any other suitable hydrogenation process.

In this example it is preferable to employ a temperature of over 100 C. Other purifying agents such as the metal ammonia compounds, potassium amid, metal carbides such as those of aluminum' or calcium or metal acetylides, can be employed. The subject matter of this last example is not specifically claimed in the present case, but in a copending cas'e filed. concurrently herewithQSerial No. 496,640.

It may he remarked that the purification of the naphthalene from those substances which produce red. coloration upon treatfinely divided metal catalyst with com it takes u ment with sulfuric acid, not onlymakes the catalyzer last better (i. e., retain its usefulness for a long period), but also it renders the hydrogenation much easier and more readily controllable.

The hi hly' impure varieties of naphthalene whic give a deep red color with sulfuric acid, can be purified according to the processes herein described, and subsequently hydrogenated.

The hydrogenation can conveniently be effected at temperatures between 125 and 260 0., and it usuallyis not advisable to employ temperatures substantially in .excess of 200 C.

\Vhat is claimed is:

1. In the hydrogenation of napthalcnc, the herein described improvement which comprises removing from 'na hthalene in molten condition all of the bodies which are capable of causing red coloration upon treat ment with strong sulfuric acid, and then hydrogenating the product while still in molten condition, by treating with hydrogen in the presence of a hydrogenation catalyst, until it has absorbed such an amount of hydrogen as to form a definite hydrid of naphthalene.

2. A process which comprises treating molten naphthalene, in the absence of 'terial amounts of cataly zer poisons, with hydrogen, in the presenceof' a nickel catalyzer, at a temperature above 100 0., while under a pressure of about 10 atmospheresr I 3 A process which comprises mlXlIlg a mercia'l naphthalene which is free from those impurities which are capable of causing red coloration when treated with strong sulfuric acid, and treating it as a non-flowing mass, with hydrogen under pressure, until such an amount of hydrogen as correspon s to the formation of a definite hydrid of naphthalene.

4. A process of hydrogenating naphthalene which comprises treating a naphthalene from naphthalene,

of commercial grade, but/free from all those impurities which are capable of producing a red coloration on treatment of said na hthalene with strong sulfuric acid, with ydrogen in the presence of a hydrogenation catalyst.

5. A process of hydrogenating na hthalene which comprises treating a naphthalene of commercial grade, but free from all those impurities which are capable of producing a red coloration on treatment of said na ,hthalene with strong sulfuric acid; with hydrogen in the presence of a hydrogenation catalyst under a pressure of about 10 atmospheres and at about 100 to 200 C.

6. In the process thalene, the step which comprises treating a of hydrogenating naphnaphthalene of commercial grade, free from all those impurities which are capable of producing a red coloration on treatment of said naphthalene with strong sulfuric acid, with hydrogen in the presence of a hydrogenation catalyst, has combined with such a drogen as to produce a de naphthalene.

7. Approcess of hydrogenating naphthalene which comprises the steps of removing from naphthalene, while in fluid condition, constituents capable of acting 'as catalyzer poisons and then subjecting the purified naphthalene, while still in fluid condition, to the action of hydro en in the presence of a hydrogenation cata yst. v 8. A lene WlllCh comprises the steps of removing while at an elevated temperature, constituents capable of acting as catal zer poisons and then subjecting the puri ed naphthalene, while still at an elevated temperature, to the action of hydrogen in the presence of a hydrogenation catalyst.

In testimony whereof I have signed my name to this. specification.

GEORG SGHROETER.

gfiantity of hyite hydrid of until the said naphthalene 

